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While there are several opportunities for the construction industry to integrate sustainable materials use in a project – from the design phase to the construction phase – there is still significant scope for the industry to be more innovative, says consulting engineering firm Arup.

“Ideally, designers should strive to assess the environmental impact of building materials based on their overall life cycle,” says Arup environmental and sustainability consultant Georgina Smit.

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This assessment involves the entire production process of each material, starting from where and how the product is sourced and manufactured, and considering the operational and end-of-life impact of that material, which indicates whether the product can be reused.

Realistically, however, the use of sustainable materials on building projects typically pertains to minimising the amount of portland cement within concrete, using either reused or Forest Stewardship Council-certified sustainable timber, encouraging local and responsible sourcing, and investigating options for reuse, says Smit.

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For example, old carpets or rocks from excavations can be used as cladding for the building, she explains.

Smit further highlights dematerialisation as another opportunity to integrate the use of sustainable materials on projects. She explains that dematerialisation is when the same building service is delivered, but with less materials, such as when an exposed concrete floor is maintained without an added finish.

Recycling waste is also a key issue when it comes to the use of sustainable materials, and this can be influenced in design and during construction, says Smit.

During the design phase, aside from specifying recycled products, design teams can ensure that the design of a building accommodates appropriate recycling storage spaces for when the building is complete and operational.

Recycling construction waste should also be a goal, says Smit, highlighting that contractors are successfully recycling 50% to 70% of their construction waste on green buildings projects Arup has worked on.

Smit tells Engineering News that Arup provided technical input into the Green Building Council of South Africa’s (GBCSA’s) Green Star SA Interiors rating tool, identifying some principles that involve looking further down the supply value chain when selecting fit-out materials, namely the use of take-back schemes, the use of products that are certified by independent third parties and the evaluation of a product’s manufacturing standards.

Smit adds that the industry’s uptake of sustainable construction and building fit-out materials could be improved by increased data relating to supply chains and material components, which could help inform a more balanced understanding of a material’s life cycle. An example of this would be data stipulating the embodied carbon of certain materials.

Embodied carbon is the amount of carbon it takes to produce a certain material from the point of extraction to the point of use. This includes carbon emitted during the mining and transporting of materials, as well as the processing into an end product.

Smit notes that more detailed information, like embodied carbon data, could be helpful for building contractors and engineers to make informed decisions when choosing and specifying sustainable construction materials and thus building more ecofriendly buildings in the future.

“In an ideal world, a government would legislate ecolabelling, which could, for example, require building material manufacturers to declare each component used in their product and the amount of energy exerted on those components,” she says.

Smit highlights that there are already some initiatives that aim to encourage valued supply chain stakeholders to reveal and nominate more information to allow for changes downstream, which will encourage the use of sustainable building materials and the knowledge of certain materials’ components.

For example, the paint industry responded to GBCSA criteria by providing more data that stipulates the testing processes and quantity of volatile organic compounds in paints.

Meanwhile, Smit tells Engineering News that the use of sustainable construction materials does not always have to be more expensive.

“Savings can be made using sustainable building materials if the materials used are recycled products, such as metal elements, used carpets and even reusable building rubble that have been excavated and/or sourced on site,” she explains.

However, availability issues might plague some sustainable construction materials, such as structural steel, which is difficult to source on the recycled market, concludes Smit.